eirs vs hers

eirs

pron
  • That which belongs to em, possessive case of gender-neutral ey, equivalent to the singular theirs and coordinate with his and hers. 

hers

pron
  • That which belongs to her; the possessive case of she, used without a following noun. 

How often have the words eirs and hers occurred in a corpus of books? (source: Google Ngram Viewer )